A manufacturing process of a spherical member to be used as, for example, a rolling element of a rolling bearing or a valving element of a ball valve often includes the step of polishing the surface of a spherical body. To this step of polishing a spherical body, there are requests for improved efficiency, reduced costs and the like. Here, polishing of a spherical body is commonly practiced using abrasive grains having a greater hardness than that of the spherical body. Accordingly, when the spherical body is made of a high-hardness material, for example, ceramic such as silicon nitride and sialon, an abrasive grain having extremely high hardness and being expensive, such as diamond and CBN (Cubic Boron Nitride) must be used.
In response to this situation, studies aiming at improved efficiency and reduced costs have been conducted and various proposals have been made (see Japanese Patent Laying-Open No. 2000-210862 (Patent Document 1) and Japanese Patent Laying-Open No. 2000-326238 (Patent Document 2)).